正电子发射断层扫描/切伦科夫光混合成像系统的研发

Yamamoto Seiichi, Hamamura Fuka, Watabe Tadashi, Ikeda Hayato, Kanai Yasukazu, Watabe Hiroshi, Kato Katsuhiko, Ogata Yoshimune, Hatazawa Jun

Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673, Japan.

Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.

Med Phys. 2014 Sep;41(9):092504. doi: 10.1118/1.4893535.

PURPOSE

Cerenkov-light imaging is a new molecular imaging technology that detects visible photons from high-speed electrons using a high sensitivity optical camera. However, the merit of Cerenkov-light imaging remains unclear. If a PET/Cerenkov-light hybrid imaging system were developed, the merit of Cerenkov-light imaging would be clarified by directly comparing these two imaging modalities.

METHODS

The authors developed and tested a PET/Cerenkov-light hybrid imaging system that consists of a dual-head PET system, a reflection mirror located above the subject, and a high sensitivity charge coupled device (CCD) camera. The authors installed these systems inside a black box for imaging the Cerenkov-light. The dual-head PET system employed a 1.2×1.2×10 mm3 GSO arranged in a 33 × 33 matrix that was optically coupled to a position sensitive photomultiplier tube to form a GSO block detector. The authors arranged two GSO block detectors 10 cm apart and positioned the subject between them. The Cerenkov-light above the subject is reflected by the mirror and changes its direction to the side of the PET system and is imaged by the high sensitivity CCD camera.

RESULTS

The dual-head PET system had a spatial resolution of ∼1.2 mm FWHM and sensitivity of ∼0.31% at the center of the FOV. The Cerenkov-light imaging system's spatial resolution was ∼275 μm for a 22Na point source. Using the combined PET/Cerenkov-light hybrid imaging system, the authors successfully obtained fused images from simultaneously acquired images. The image distributions are sometimes different due to the light transmission and absorption in the body of the subject in the Cerenkov-light images. In simultaneous imaging of rat, the authors found that 18F-FDG accumulation was observed mainly in the Harderian gland on the PET image, while the distribution of Cerenkov-light was observed in the eyes.

CONCLUSIONS

The authors conclude that their developed PET/Cerenkov-light hybrid imaging system is useful to evaluate the merits and the limitations of Cerenkov-light imaging in molecular imaging research.

目的

切伦科夫光成像技术是一种新型分子成像技术，它利用高灵敏度光学相机检测高速电子产生的可见光子。然而，切伦科夫光成像的优势仍不明确。如果开发出一种PET/切伦科夫光混合成像系统，通过直接比较这两种成像方式，切伦科夫光成像的优势将得以阐明。

方法

作者开发并测试了一种PET/切伦科夫光混合成像系统，该系统由一个双头PET系统、位于受试者上方的反射镜以及一个高灵敏度电荷耦合器件（CCD）相机组成。作者将这些系统安装在一个黑箱内用于切伦科夫光成像。双头PET系统采用了排列成33×33矩阵的1.2×1.2×10 mm³GSO，其与位置灵敏光电倍增管进行光学耦合以形成一个GSO块状探测器。作者将两个GSO块状探测器相隔10 cm放置，并将受试者置于它们之间。受试者上方的切伦科夫光被镜子反射，改变方向射向PET系统一侧，并由高灵敏度CCD相机成像。

结果

双头PET系统在视野中心的空间分辨率约为1.2 mm半高宽，灵敏度约为0.31%。对于²²Na点源，切伦科夫光成像系统的空间分辨率约为275μm。使用组合式PET/切伦科夫光混合成像系统，作者成功从同时采集的图像中获得融合图像。由于切伦科夫光图像中受试者体内的光传输和吸收，图像分布有时会有所不同。在对大鼠的同步成像中，作者发现PET图像上¹⁸F-FDG主要积聚在哈德腺，而切伦科夫光分布在眼睛中。